Cross flow cooling system plumbing.
prawnabie - 19/9/09 at 09:07 PM
I am going to re-plumb the cooling system on my crossflow over the next few weeks. I want to be able to see the cooling level whilst the engine is hot
and the current setup does not let you do that!
The current system is very simple. The system is filled via the filler neck on the head, and the outlet on the inlet manifold its plumbed back into
the water pump. The is only 1 radiator cap, this being on the filler neck, the one on the rad has been cut off and welded over. THe drawings below all
have the "filler neck" thermostat housing subtituted for a standard elbow with a take-off on it.
Whith regards to plumbing the tank in, I have come up with a few options.
1) Connect the take-off on the thermostat housing to the top inlet on the tank. Put a T in the line from the inlet manifold to the pump and run this
to the bottom of the bottle.
Image deleted by owner
2) Same as above but with the bottom of the tank plumbed into a take off on the bottom hose.
Image deleted by owner
There are a few other ideas such as cutting the line from the inlet manifold to the pump and connecting both lines to the expansion tank?
Has anyone done this and can shed some light?
Thanks
Shaun
Also, there is a large volume of air in the radiator due to the filler neck being cut off and rewelded over. This air cannot escape due to the angle
of the rad. Is this a bad thing (should I weld a take off into the top of the rad) or is it ok?
[Edited on 19/9/09 by prawnabie]
adithorp - 19/9/09 at 09:23 PM
I'd say the second one and if you can put a bleed pipe into the top of the rad and T the other end into the bleed pipe between the thermostat and
the top of the bottle then that will help make it a bit more efficient.
In the first picture when the thermostat is closed the pump will try to circulate water through the bottle and bleed pipe back to the rad.
adrian
prawnabie - 19/9/09 at 10:01 PM
You mean like this Adrian?
Image deleted by owner
If I go for that setup, is it advisable to keep the 1/8 hole drilled in the thermostat - will it cause any problems?
prawnabie - 20/9/09 at 09:26 AM
Anybody got a take on this?
02GF74 - 20/9/09 at 09:33 AM
quote:
Originally posted by adithorp
In the first picture when the thermostat is closed the pump will try to circulate water through the bottle and bleed pipe back to the rad.
hmm, I think both will. the pump pushes water out so in both cases water will be pused into the header - makes no different if the connection is
between radiator and pump (2) or manifold and pump (1).
.... unless someone says I am wrong ...
rusty nuts - 20/9/09 at 09:34 AM
quote:
Originally posted by adithorp[/
In the first picture when the thermostat is closed the pump will try to circulate water through the bottle and bleed pipe back to the rad.
adrian
More likely to circulate coolant from the inlet manifold outlet back into the water pump , Some coolant may circulate through the header but not a
lot.
The first diagram with the additional bleeder from the top of the rad is how mine is plumbed in although mine has a heater plumbed between the
inlet manifold and the water pump union with an inline bleed valve to make filling/bleeding easier. Have had no overheating problems in all the time
the car has been on the road
prawnabie - 20/9/09 at 01:31 PM
Im confused now lol!
When the thermostats closed, water should circulate through the "bypass" pipe from the inlet manifold to the water pump.
When the stat opens, water will maily pass through the rad, with some water passing though the bypass pipe and into the header tank. The same will
happen with a small amount of water from the top of the radiator.
Am I right in thinking that most of the coolant will still flow through the raidiator?
rusty nuts - 20/9/09 at 01:54 PM
Yes but only with the thermostat open. In answer to O2GF74 post, the pump does not" push out" it in fact "pulls in" . Water
circulates "out " of the thermostat housing , through the rad and is drawn in through the water pump . Thermosython is the correct term
IIRC. There will always be some circulation through the header tank
prawnabie - 20/9/09 at 01:56 PM
One last question lol!
If I go with the last setup, should i still run with the 1/8 hole drilled in the stat, or will this make the system less efficient?
[Edited on 20/9/09 by prawnabie]
Russell - 20/9/09 at 02:08 PM
The first one works fine on my crossflow powered car EXCEPT I ended up deleting the small return hose from the top of the stat housing to the
expansion bottle (use small stoppered lengths of hose to blank off each end).
I can't remember exactly why I got rid of that hose - something to do with it creating air locks, despite the fact that I think it's
intended to stop them by bleeding air from a high point back to the bottle. 3K miles later and it's still working fine 
.
BTW I made the tee at the manifold from 15mm copper fittings but wrapped in black tape to blend in. That also has been 100% durable for several years
and many miles.
I fitted a small bleed screw onto the top of the rad to get rid of excess air. If you have brass rad just clean back to shiny metal then solder on a
brass nut. Once fitted, punch a small hole down in the centre of the nut and use a cut down brass screw and fibre washer to seal it.
Hope that helps!
Russ
adithorp - 21/9/09 at 07:41 PM
Yes, your right.
The updated picture is what I meant with the rad bleed. Thats how most manufactureers do it.
adrian